A Practical, Noninvasive Urine Collection Method for Mice for Large Cohort Preclinical Studies.

Accurate urine collection is essential for preclinical studies involving metabolism, toxicology, and disease modeling. However, conventional methods such as metabolic caging and manual restraint are often invasive, labor intensive, prone to contamination, and not scalable for large cohorts, while also raising animal welfare concerns. This study presents a noninvasive and practical technique for collecting spot urine samples from healthy and tumor-bearing mice developed as a refinement to existing collection approaches. The method involves positioning the mouse in a natural voiding posture by allowing the hindlimbs to hang freely while the forelimbs grip a wire bar feeder, thereby stabilizing the animal and reducing excessive movement. Gentle abdominal pressure is applied only when needed. The method was validated in 80 C3H/HeJ and athymic nude mice, including both healthy and tumor-bearing (fibrosarcoma or prostate cancer [PC3]) models. Using this approach, spot urine volumes ranging from 13 to 200 µL were reliably collected from all mice, with each successful collection completed within 1 minute. Urine was successfully collected on the first attempt in ∼70% of cases. The mean urine yield was 51.7 ± 38.9 µL for healthy females, 53.7 ± 28.5 µL for healthy males, 50.8 ± 20.2 µL for tumor-bearing females, and 52.2 ± 28.1 µL for tumor-bearing males, with no statistically significant difference (P > 0.05) in urine volume distributions between groups. No visible fecal or particulate contamination was observed during sample collection. The collected volumes are sufficient for a wide range of molecular and metabolic analyses, ensuring the method's applicability in diverse research settings. Unlike other techniques that involve excessive handling, this method requires no restraint devices, making it well suited for large cohort studies and repeated sampling. The proposed technique represents a practical refinement in preclinical research by offering an optimal balance between sample quality, animal welfare, and experimental efficiency.